A SORGHUM TRAP CROP TO PREVENT STINK BUGS FROM INFESTNG ORGANIC TOMATOES

By

ALEXANDER MICHAEL GANNON

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2019 1

© 2019 Alexander Michael Gannon

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To my Mom, Dad, and Elizabeth, who were there, supported, and loved me throughout my life and graduate studies. To my friends and rest of my family, thank you for the motivation to keep going and the constant support

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ACKNOWLEDGMENTS

I would like to thank Dr. Norman Leppla, Dr. Amanda Hodges, Dr. Oscar Liburd, and Dr. Xin

Zhao for all the support and assistance throughout the master’s thesis. The guidance provided by my graduate committee allowed me to succeed and develop throughout the two years of this research. The thesis was supported with partial funding by United States Department of

Agriculture, National Institute of Food and Agriculture, Crop Protection and Pest Management, and Extension Implementation Program.

I would also like to thank Kylie Lennon, an undergraduate assistant for tremendous help collecting stink bugs in the field, rearing the colony of Nezara viridula, and acquiring data from the collected specimens. Additionally, I would like to thank Jennifer Carr for the assistance scouting in the field at Live Oak and guidance on rearing stink bugs.

Lastly, I want to thank the whole staff at the North Florida Research and

Education Center at Suwannee Valley. Without Bob Hochmuth, Ben Broughton, Jerry Butler,

Wanda Laughlin, Tim Norris, Mike Boyett, and Zach Hill, I would not have not been able to complete my research from germinating the tomato seeds to harvesting tomatoes at the end of the season. Thanks to Dr. Danielle Treadwell for guidance on maintaining a certified organic farm and Chromatin Inc. for donating untreated sorghum seeds.

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TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ...... 4

LIST OF TABLES ...... 7

LIST OF FIGURES ...... 8

ABSTRACT ...... 10

CHAPTER

1 LITERATURE REVIEW ...... 12

Importance of Florida Tomato Production ...... 12 Market for Florida’s Conventional and Organic Tomatoes...... 12 Organic Tomato Production ...... 12 Stink Bug Pests of Tomato in Florida ...... 13 Nezara viridula ...... 14 Euschistus servus ...... 14 Euschistus quadrator ...... 15 Current Threat from Halyomorpha halys (Stal) ...... 16 Stink Bug Damage to Tomato ...... 16 Nezara viridula Feeding Injury and Damage ...... 16 Stink Bug Feeding Damage Assessment ...... 17 Stink Bug Reproduction Based on Nezara viridula ...... 17 Stink Bug Diapause and Ovary Development ...... 17 Stink Bug Development from Egg to Adult ...... 18 Integrated Pest Management...... 19 Trap Cropping Systems ...... 19 Perimeter Trap Cropping ...... 20 Sorghum Trap Crop and Stink Bugs ...... 21 Sampling Methods for Stink Bugs ...... 21 Stink Bug Collection Techniques ...... 22 Stink Bug Parasitoids ...... 23 Trissolcus basalis ...... 23 Trichopoda pennipes ...... 23 Predators of Stink Bugs ...... 24

2 A SORGHUM TRAP CROP TO PREVENT STINK BUGS FROM INFESTNG ORGANIC TOMATOES ...... 27

Introduction...... 27 Materials and Methods ...... 28 Site Description ...... 28 Experimental Design ...... 28

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Stink Bug Collection ...... 29 Stink Bug Identification ...... 30 Four Most Abundant Stink Bug Species Collected on Sorghum and Tomato ...... 30 Tomato Injury ...... 30 Statistical Analysis ...... 31 Stink bug counts ...... 31 Injury ...... 32 Stink Bug Reproductive Status ...... 32 Stink Bug Parasitism ...... 33

3 RESULTS AND DISCUSSION ...... 38

Results ...... 38 Stink Bug Species Collected on Sorghum and Tomato ...... 38 Stink Bug Measurements ...... 38 Sex and Stage of the Four Most Abundant Stink Bug Species Collected Each Week on Sorghum and Tomato ...... 38 Weekly Occurrence of the Four Most Abundant Stink Bug Species in Each Row of Sorghum and Tomato ...... 40 Nezara viridula in sorghum...... 40 Nezara viridula in tomato ...... 40 Piezodorus guildinii in sorghum ...... 41 Euschistus servus in sorghum ...... 41 Euschistus servus in tomato ...... 42 Euschistus quadrator in tomato ...... 42 Tomato Damage by Stink Bug Species ...... 42 Egg Development in Nezara viridula, Piezodorus guildinii, and Euschistus servus ...... 42 Parasitism of Nezara viridula by Trichopoda pennipes ...... 43 Discussion ...... 44 Stink Bug Abundance on Sorghum and Tomato ...... 44 Stink Bug Injury to Tomato ...... 45 Stink Bug Measurements ...... 45 Evaluation of the Study ...... 46 Conclusion ...... 46

LIST OF REFERENCES ...... 65

BIOGRAPHICAL SKETCH ...... 70

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LIST OF TABLES

Table page

3-1 Total number of stink bug species collected during the study...... 48

3-2 Mean (+SD) length and width (in millimeters) of all male and female stink bugs of each species collected in sorghum and tomato...... 49

3-3 Total number of male, female and nymph stink bugs of the four most common species collected on all rows of sorghum and tomato during each week of the study...... 50

3-4 Mean (+SD) number of Nezara viridula collected in each row and week in the sorghum trap crop...... 51

3-5 Mean (+SD) number of Nezara viridula collected each week in treated and untreated rows of tomatoes. P-value was determined by combining treated and untreated tomato each week...... 52

3-6 Mean (+ SD) number of Piezodorus guildinii collected each week and row in the sorghum trap crop...... 54

3-7 Mean (+SD) number of Euschistus servus collected in each row and week in the sorghum trap crop...... 56

3-8 Mean (+SD) number of Euschistus servus collected in each row and week in the treated and untreated tomato crop...... 57

3-9 Mean (+SD) number of Euschistus quadrator collected in each row and week in the treated and untreated tomato crop...... 58

3-10 Mean (+SD) number of Nezara viridula, Eushistus servus, and Euschistus quadrator feeding sites on tomato each week...... 60

3-11 Mean (+ SD) ovary development and egg content for Nezara viridula, Piezodorus guildinii, and Euschistus servus females collected each week in the first and eighth rows of sorghum...... 62

3-12 Ovary development and egg content for Nezara viridula, Euschistus servus and Euschistus quadrator females collected each week in the rows of tomato...... 63

3-13 The percentage of Nezara viridula parasitized by Trichopoda pennipes each week in both sorghum and tomato...... 64

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LIST OF FIGURES

Figure page

1-1 Left, adult southern green stink bug, Nezara viridula. Middle; N. viridula stink gland pore. Right, Chinavia halaris stink gland pore. Photograph and diagrams by James Castner, University of Florida...... 24

1-2 (A) Dorsal view of the brown stink bug. (B) Ventral view if a female brown stink bug. Photographs by W. Louis Tedders & Herb Pilcher, USDA, Bugwood.org...... 25

1-3 (Right) Dorsal view of E. quadrator. (Left) Ventral view of E. quadrator. Confirmed by Joseph Eger. Photograph by Michael Grodowitz...... 25

1-4 Three diagnostic features to distinguish between E. servus. Banding on the antennae, alternating bands on the margin of the abdomen, and no humeral spines. Photograph by Lyle J. Buss...... 25

1-5 Stink bug Dichelops furcatus feeding on wheat Triticum aestivum L. The stylet is penetrating the stem epidermis into the tissue. Ep is the stem epidermis and Pa is the parenchyma. Photographs by Tiago Lucini and Antonio R Panizzi, 2017...... 26

1-6 Stink bug damage produced by adults and nymphs feeding on the tomato. The cloudy blotches are white to yellow in color and creates a spongy tissue underneath the epidermis. Photo by Gannon 2018...... 26

2-1 North Florida Research and Education Center- Suwannee Valley (research and demonstration farm) with organic field plot (red) in inset. Photo by Alexander Gannon, 2018...... 34

2-2 Field plot experimental design with sorghum trap crop sections adjacent to the tomato crop (treated, T) or no trap crop (untreated) ...... 35

2-3 Width of N. viridula measured from the end of the left and right humeral spines. Photo by Alexander Gannon, 2018...... 36

2-4 Tomatoes from a section in a row (A) and marked with sharpie where damage occurred (B). Photo by Alexander Gannon, 2018...... 36

2-5 Heavy eggs present in N. viridula. A. Mature eggs. B. Expanded spermatheca. Photo by Alexander Gannon, 2018...... 37

2-6 Parasitoid egg and length of male N. viridula. Photo by Alexander Gannon, 2018...... 37

3-1 The mean number of Nezara viridula in treated and untreated tomato sections through seven weeks...... 53

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3-2 Mean (+SD) number of Piezodorus guildinii and Nezara viridula captured in sorghum rows 1-3 plus 6-8...... 55

3-3 The mean (+SD) number of Nezara viridula, Euschistus servus, and Euchistus quadrator in combined treated and untreated tomato subplots per week...... 59

3-4 Mean (+SD) number of feeding sites each week on treated and untreated tomatoes...... 61

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science

A SORGHUM TRAP CROP TO PREVENT STINK BUGS FROM INFESTNG ORGANIC TOMATOES

By

Alexander Michael Gannon

August 2019

Chair: Norman Leppla Major: Entomology and Nematology

Cultural control methods are needed for organic farmers that have limited resources available to reduce stink bugs (Hemiptera: Pentatomidae) from causing direct injury to tomatoes, rendering them unmarketable. Sorghum was planted on the east and west sides of a tomato crop in a certified organic field to prevent stink bugs from damaging the tomatoes. In the seven-week study, 10 species of stink bugs were found, with Nezara viridula, Piezodorus guildinii,

Euschistus servus, and Euschistus quadrator being the four primary stink bugs occurring in sorghum or tomato. Nezara viridula and E. servus had a female biased sex ratio and were the predominant species found on tomato, along with E. quadrator. Nezara viridula, P. guildinii, and

E. servus. The sex, stage, average length, and width were determined for each of the stink bug species collected. The average weekly abundance of the four primary stink bugs in the east and west side of the field was determined in both sorghum and tomato. The sorghum attracted stink bugs to each of the rows planted but did not prevent N. viridula from infested the tomato crop, causing tomato injury to exceed the USDA market standards of 0.0095 m in diameter. The N. viridula females were dissected and their ovaries had a heavy egg content by the 4th week (July

12th, 2018), whereas P. guildinii and E. servus produced very few eggs. About 10% of the N. viridula adults were parasitized by Trichopoda pennipes (Diptera: Tachinidae). These results

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may assist organic and conventional tomato producers in adopting trap cropping options for integrated pest management.

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LITERATURE REVIEW

Importance of Florida Tomato Production

Market for Florida’s Conventional and Organic Tomatoes

Fresh fruit and vegetables are the top organically grown food that accounts for 43% of the U.S. organic food sales in 2012 (USDA-ERS 2017). Florida is the main vegetable supplier for the entire U.S. during the late fall, winter, and early spring, which allows for more than 40 vegetable crops to be planted (Vallad et al. 2018). The total production of fresh market tomatoes in Florida account for 34% of the entire U.S tomato value, bringing in approximately $262 million per year. Tomatoes were ranked second in the 2017 value of vegetable, melon, and berry production with cucumbers, grapefruit, oranges, squash, sugarcane, fresh market snap beans having 47,000 commercial farms throughout Florida (FDACS 2017). Organic tomatoes have become high in demand for local and wholesale markets. Organic tomato production requires a greater investment than conventional production. Consumer demand for organic food has continued to grow at a steady pace of 20% or more annually since the 1990s with 73% of conventional grocery stores and 100% of natural food stores having organic products (Nguyen et al. 2015).

Organic Tomato Production

Organic farming employs methods of production that utilize non-synthetic inputs and emphasizes biological and ecological processes to improve soil quality, manage soil fertility, and optimize pest management (Treadwell and Perez 2017). In organic crop production throughout

Florida, 58% of the growers produce vegetables, with 38% of these vegetables being the primary crop sold for each season (Nguyen et al. 2015). There are several advantages of using organic production strategies to grow vegetables, including tomatoes. Reducing the use of insecticides

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and herbicides promotes biodiversity and preserves ecosystem services. Moreover, organic production uses less energy and produces minimal waste compared with conventional farming.

In both organic and conventional farming, nutrient sources are crucial for plant growth, yield, and quality. Synthetic fertlizers are less frequently used in organic production, therefore, an increase in crop rotation, farm manure, green manure, and compost is required. Organic tomato yield was 63% of conventional yield comparing three organic farms to conventional production

(Riahi et al. 2009). Cost of producing tomatoes in organic systems was determined after comparison to IPM and conventional systems. The total cost of organics was $16,029.11 comapred to $14,346.65 of convertional costs. The net returns from all three systems were

$34,541, $34,288, and $22,659 for conventional, IPM, and organic tomato systems (Brumfield et al. 1993).

Stink Bug Pests of Tomato in Florida

Stink bugs are in the Pentatomidae family and considered economically important due to feeding on vegetables, fruit, nuts, and grain crops. Stink bugs can cause losses exceeding $60 million in soybean in the southeastern United States (McPherson and McPherson 2000). More importantly, stink bugs feed on the Solanaceae family which include tomatoes and peppers.In

2002, stink bugs have injured 26-39% of spring tomatoes in Virginia. The cost to control stink bugs and damage caused was approximately $28.29 per hectare in Mississippi (Herbert and

Toews, 2012). The southern green stink bug, Nezara viridula (L.); brown stink bug, Euschitus sevus (Say); and the brown marmorated stink bug, Halymorpha halys (Stal), feed on tomatoes.

Stink bugs can be especially damaging in open-field production due to their movement from crop to crop but can be excluded in protected culture via greenhouses and high tunnels (Leppla et al.

2017). High tunnels are structures that are protected on two sides instead of four sides similar to

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that of a greenhouse. In Florida, high tunnels are used in the fall and winter because of the increase in temperatures during the summer.

Nezara viridula

The southern green stink bug has many common names: green stink bug, green vegetable bug, green soldier bug, southern green plant bug, tomato and bean bug, and green bug of India.

The official common name, the southern green stink bug, is listed in the Entomological Society of America Common Names of Insects Database (https://www.entsoc.org/common-names).

Nezara viridula occurs worldwide and has been studied in the tropical and subtropical regions of the Americas, Africa, Asia, Australia, and Europe (Todd 1989). Nezara viridula is in the taxonomic order Hemiptera and suborder Heteroptera. Adult N. viridula are green, have four antennal segments, and are approximately 12 mm long but females can be larger than males at approximately 13 mm in length (Jeram and Pabst 1996). The green color can become red-brown due to diapause. Three white dots are visible on the front edge of the scutellum where it joins the prothorax and two small black dots occur on the anterior corners of the scutellum. An important distinguishing character is the shape of the stink gland pore, which is short and broad, compared to other stink bug species (Fig 1-1) (Squitier 2013).

Euschistus servus

The brown stink bug occurs in North America, most commonly in the southeast U.S. and west through Louisiana, Texas, New Mexico, Arizona, and California. This pest is highly polyphagous feeding on a range of grasses, shrubs, and trees. The brown stink bug is of economic importance on soybean, alfalfa, pecan, sorghum, corn, peach, pear, apple, cotton, tomato, sugar beets, and tobacco. The nymphs and adults of this species will feed on the green fruits of tomato, which can cause the fruit to have a bitter taste and pithy texture (McPherson &

McPherson 2000). Euschistus servus has been found to cause more feeding injury in the spring

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than the fall tomato fruit. Injury caused by the brown stink bug to tomatoes is greater if planted late in May compared to earlier spring planting in April (Nault & Speese 2002). Euschistus servus has been found to occasionally be a predaceous pest on the cotton worm, mountain-ash sawfly, and the imported cabbageworm (McPherson & McPherson 2000). Adult E. servus can range from 10 to 15 mm for adults depending on the sex. The adults are grayish-yellow with dark punctures on the dorsal pronotum and scutellum (Figure 1.2) and the ventral surface has a pink to green color (Gomez et al. 2008). Males are distinguished from females by a scooped shape structure on the posterior end of the genitalia. The brown stink bug overwinters as adults under crop residues, bark, grasses, and leaves. As adults begin to overwinter and diapause, the bodies become mottled with light reddish spots (Mizell 2005). The adults emerge during the spring similar to that of other Pentatomidae species and this is due to photoperiod and temperature.

Females can produce as much as 18 egg masses over 100 days with four to five generations produced per year in Florida. Eggs are yellow, becoming pink before hatching with the nymphal stages taking approximately 29 days to go through five instars (Gomez et al. 2008).

Euschistus quadrator

Euschistus quadrator is part of the lesser brown stink bug complex that occurs in the southeast U.S including Alabama, Florida, Georgia, North Carolina, South Carolina, and

Virginia. This pest is a polyphagous stink bug that has a host range of soybean, cotton, corn, peanuts, wheat, tomato, and alfalfa. Euschistus quadrator can be distinguished from other species by the lack of pigment on the hemelytra (Blackman et al. 2017).This pest has a body length less than 11 mm and the posterior margin of the genital cup is broad and flat across the width, a distinguishing feature between E. servus (Eger unpublished). Eggs for this species begin semi-translucent and turn light yellow to red during maturation. The nymphs go through five instars until becoming adults with color and size can varying (Brennan et al. 2012).

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Current Threat from Halyomorpha halys (Stal)

The brown marmorated stink bug (BMSB) is an invasive stink bug introduced to the U.S. from China in the mid-1990s. Halyomorpha halys has caused $37 million in losses to apples, peaches, nectarines, tomatoes, peppers, sweet corn, and soybeans (Leskey and Nielsen 2018).

This pest is not established in Florida as of yet, but FDACS-DPI has declared H. halys a regulatory significant pest of limited distribution. Eggs and nymphs of the brown marmorated stink bug were found in May 2018 at Lake County, Florida (Penca 2018). If this pest were to establish in Florida, it would create more economic loss for fruits and vegetables including tomato. BMSB emerge from overwintering in April with numbers increasing throughout late spring. Females can lay an average of 9.3 egg masses, beginning light green to white when hatching (Leskey and Nielsen 2018). The nymphs will go through five instars before becoming adults. Halyomorpha halys adults are distinguished between the native U.S. stink bug E. servus by the white and black banding on the antenna and abdominal edges alternating in dark and light bands (Figure 1.4) (Rice et al. 2014). Adults range from 12 to 17 mm in length, have no humeral spines, and can have a range of colors from brown to black on the dorsal surface (Penca and

Hodges 2019).

Stink Bug Damage to Tomato

Nezara viridula Feeding Injury and Damage

The southern green stink bug prefers seed heads and fruiting structures and can cause heavy feeding damage to fresh market tomatoes (Lye et al. 1988). By inserting their stylets into the fruit, the stink bugs create cloudy blotches and surface depressions on tomatoes. This injury decreases the marketability of the fruit. The stylets are surrounded by sheaths that facilitate penetration and seal puncture sites (Will & Vilcinskas 2015). Higher numbers of stink bugs on tomato fruit will cause an increase in injury. The number of stylet sheaths was higher with six N.

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viridula compared to two per fruit. Deposition of stylet sheaths does not decrease fruit size but reduces the grade and creates unmarketable fruit. Damage to tomatoes increases as more stink bugs are present in the field (Lye et al. 1988). It can induce early maturation, reducing fruit size, weight and grade (United States Department of Agriculture 2005). If more than four N. viridula infest a fruit, the circumference decreases significantly (Lye et al. 1988). An increase in tomato damage from N. viridula ranged from 17 to 22% as insecticide applications were reduced

(McPherson and McPherson 2000).

Stink Bug Feeding Damage Assessment

Tomatoes are graded for marketable yield based on multiple elements from harvest to storage (USDA 2005). The USDA standards for tomato considers size, weight, and defects.

USDA standard tomato defects include quality and condition. By USDA standards, the injury that stink bugs produce is graded based on quality, which is a light-colored area, silvery white to yellow with indistinct borders, occurring in the fleshy tissue under the epidermis. The scoring guide for this defect is based on three levels: Damage, serious damage, and very serious damage.

The damage is measured by the diameter of the spot. Damage is 0.0095 m in diameter, serious damage is 0.025 m diameter, and very serious damage is more than 0.025 m in diameter (USDA

2005). This scale was used to determine what tomatoes in this study were marketable.

Stink Bug Reproduction Based on Nezara viridula

Stink Bug Diapause and Ovary Development

Diapause is an important factor in determining when insects can reproduce. Nezara viridula has different diapause induction behaviors throughout the world. While some N. viridula go into a reproductive diapause in bark, litter or shelters, others do not diapause and instead relocate to alternative host plants (Musolin et al. 2003). This can depend on the temperature during the winter and photoperiod as an important environmental factor. Under long-day

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photoperiods, N. viridula are reproductive while short day photoperiods induce diapause

(Musolin 2012). Critical day-length for diapause induction ranges between 10 and 12 hours while a daily 13-hour photophase suppresses diapause (Todd 1989). Reproductive organs are different in reproductively active compared with diapausing females. In active females, the eggs are chorionated or have vitellogenic oocytes in the ovarioles. The fat body is weakly developed and loose in diapausing females and differentiation and development of oocytes is interrupted

(Musolin 2012). The ovarioles tend to be clear and no oocytes are present in the germaria. It is thought that females going into a diapausing state will arrest ovarian development, consume accumulated fat in their fat bodies, and become light brown to brown in color (Todd 1989). The fat bodies of diapausing females are dense and massive. Male reproductive organs can change during diapause but females are easier to observe. Stink bugs body color is indicative of stink bug species in diapause and smaller reproductive organs. Once a reversion of original color appears on the species of stink bug, diapause termination begins allowing active development and post- diapause reproduction (Musolin 2012). Determining the state of female ovary development is important because it indicates when stink bug diapause is terminated and they begin feeding on attractive crops.

Stink Bug Development from Egg to Adult

Initially, N. viridula eggs are yellow to cream colored but become orange prior to hatching (Todd 1989). The eggs are oviposited in polygonal clusters, 30-130 eggs per mass.

Incubation of the eggs can take 5 days to 3 weeks depending on the season and environmental conditions. Approximately 3 days after oviposition, the embryo may be visible as a red crescent

(CABI 2018). As the life cycle progresses, N. viridula develop through five nymphal instars. The first instar nymphs usually aggregate on their egg mass, which they can use as a food source.

Adequate water accelerates development of the nymphs to the first molt. After the first molt, the

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nymphs move away from the egg mass and begin to feed on plants. The third instar nymphs tend to aggregate, perhaps resulting in protection from predators. At the fourth instar, they disperse into fields and crop plants. Each of these instars can last for approximately one week. The fifth instar nymphs become green and responsive to adult pheromones and day length, potentially resulting in diapause of the adult stage. Development from egg to adult takes 23-58.4 days (Todd

1989). Adults terminate diapause in early spring and immediately search for food and mates. The females can oviposit 3-4 weeks after becoming adults (Squitier 2013). When ovipositing, females usually stay on a crop for a shorter period than males as they move and feed. The adults feed on tender growing shoots, seed heads and fruit of host plants. (Todd 1989).

Integrated Pest Management

Integrated pest management is a strategy that prevents insects from injuring a crop by implementing biological control, habitat manipulation, cultural practices, and plant resistance.

This strategy is crucial for organic farms because of the reduced registered synthetic products that can eliminate pests. In conventional systems, all registered inseciticides, herbicides, and fungicides are applicable to the field, therefore, organic production needs to apply alternative methods to efficiently manage pests. Conventional system spray applications are cheaper with the average of $797.84 used for insecticides. Organic systems use more applications with organic insecticides with the average of 1,504.89 (Brumfield et al. 1993). Alternative IPM strategies need to be incorporated to reduce the cost gap between conventional and organic growing systems.

Trap Cropping Systems

Trap cropping has been defined as “plant stands grown to attract insects or other organisms like nematodes to protect target crops from pest attack, preventing the pests from reaching the crop or concentrating them in a certain part of the field where they can be

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economically destroyed” (Shelton and Perez 2006). Trap cropping systems have been studied and implemented throughout the world, including the U.S. (Hokkanen 1991). Successful trap cropping systems for vegetables include perimeter, multiple trap crops, push-pull, and sequential

(Shelton and Perez 2006, Balusu et al. 2015). Cotton and soybean have been the most studied crops with different systems to protect against hemipteran insects. Trap cropping systems for cotton, soybeans, potatoes, and cauliflower were successful in controlling eleven pest species:

Lygus Hesperus (Knight), Lygus elisus (Van Duzee), Anthonomus grandis (Boheman), Nezara viridula, Euschistus spp. (Dallas), Acrosternum hilare (Say), Piezodorus guildinii (Westwood),

Epilachna varivestris (Mulsant), Cerotoma trifurcate (Forster), Leptinotarsa decemlineata (Say), and Meligethes aeneus (Fabricius) (Hokkanen 1991).

Perimeter Trap Cropping

Perimeter trap cropping is the utilization of the trap crop around the border of the main cash crop. This technique has been used for the southern green stink bug, Nezara viridula, with mustard to protect corn (Shelton and Perez 2006). Perimeter trap cropping has been used with N. viridula for cotton, soybean, and researched for tomato (Gordon et al. 2017). Using soybean as a trap crop for cotton is more effective than stand-alone pheromone-baited traps in deterring colonization by stink bugs (Tillman et al. 2015). The perimeter strategy also can include multiple trap crops or the use of pheromones within the crop. Staggered perimeter trap cropping paired with multiple trap crops of sunflower and sorghum varieties were used to surround tomatoes in

Alabama. This strategy was successful for intercepting leaf-footed bugs and some species of stink bugs (Stivers 2012). Perimeter trap crops should be placed between the suspected sources of stink bugs and the target crop borders to intercept incoming adults (Gordon et al. 2017). For smaller acreages, it may be best to plant the trap crops around the entire target crop perimeter.

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Long narrow plots are recommended when the target crop is susceptible to feeding damage and the trap crops will be highly attractive to stink bugs.

Sorghum Trap Crop and Stink Bugs

Highly attractive trap crops for N. viridula are sorghum (Sorghum bicolor (L.) Moench spp. Bicolor), sunflower [Helianthus annuus (L.)], buckwheat [Fagopyrum esculentum

(Moench)], millet [Pennisetum glaucum (L.)], and triticale [Triticosecale (Wittm)] (Mizell et al.

2008). Sorghum is one of the most important trap crops for N. viridula and it attracts other major stink bug pests, such as Piezodorus guildinii (Westwood) the brown stink bug, Euschistus servus

(Say), green stink bug; Chinavia hilare (Say), dusky stink bug; Euschistus tristigmus (Say), and the eastern leaf-footed bug; Leptoglossus phyllopus (L.) (Mizell et al. 2008). When sorghum is used as the trap crop, seed heads remain in the optimum growth stage for 2-4 weeks, although ratooning to a height of 0.5-0.75 m can extend their usefulness. The plants develop multiple stalks and set new heads in 3-4 weeks but remain shorter and have unsynchronized seed formation. It is preferred to plant the sorghum trap crop with a range of maturity dates.

Sampling Methods for Stink Bugs

Determining the behavior of stink bugs allow for successful sampling methods when designing field trials and capturing the population. Sampling grids are used in field trials to determine population size of stink bugs. Geographical Information Systems (GIS) and GPS coordinates are used in fields to determine spatial location of samples. Depending on the size of field plots, stink bug samples can be taken by either sections of a grid or by the whole field.

Studies have sampled along different transects from the edge of the field (Reay-Jones 2010).

Stink bug species aggregate in alternate host plants near the edge of the field (Reay-Jones 2010), so sampling along the edge can determine where the population is coming in from and how far away stink bugs are traveling from an alternate host. Intensive sampling has been utilized not

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only in field edges but also corners and sides that are adjacent to alternate host for stink bugs

(Cullen and Zalom 2000). Stink bug aggregation within the field causes many of the studies to reject a complete randomization field design. If a field sample is large, the plot can be subdivided and stink bug samples can be collected in the subplot area (Tillman 2006). Setting up field designs and taking the data is an important step into stink bug sampling. How to collect the stink bugs is a crucial step in acquiring enough samples from the field.

Stink Bug Collection Techniques

Stink bugs can be collected by shaking the plant canopy over a beat cloth, sweep netting, and hand picking in a field. Collection techniques can be used together, for example tracking the movement of N. viridula with a radar tag involved both sweeping and beat cloth sampling

(Pilkay et al. 2013). The collection technique also varies based on the crop and trap crop being used in the study. If the host plant are trees or forage crops such as soybean, sweep netting is a more accurate method to collect stink bug pests. When sweep netting, the number of sweeps per plant is kept uniform so the data will not be skewed. In shrubs, beat cloth samples and sweep netting can be used depending on the shrub. Beat netting can also be used for vine hosts and sweeping netting for herbs (Jones and Sullivan 1982). These collection techniques have strengths and weaknesses. Sweep netting and ground cloth sampling has been compared for sampling pest in soybean. Both of these techniques were effective in capturing pest, but the sweep netting method appears to be more economically efficient than the ground cloth method (Rudd and

Jensen 1977). Hand collecting techniques can be effectively used with certain trap crops and crops in which the plot is small and to reduce the damage to the plants. In tomatoes, canopy shaking has been found to be a good collection technique for stink bug species. Cafeteria trays are placed in the planting beds and the canopy is beat a certain number of times. This has found to dislodge nymphs and adults from tomato plants (Cullen and Zalom 2000).

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Stink Bug Parasitoids

The primary parasitoids of stink bugs in the Southeast are the egg parasitoid, Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae), and the nymph and adult parasitoid,

Trichopoda. Pennipes (Fab.) (Diptera: Tachinidae). The tachinids parasitize specific species of stink bugs based on the male pheromone (Tillman et al. 2010). Trichopoda pennipes is attracted to sesquiterpenoid pheromone blends of A. hilare and N. viridula: whereas, Cylindromyia spp.are primarily parasitoids of E. servus.

Trissolcus basalis

Trissolcus basalis parasitizes the southern green stink bug in vegetable crops, such as tomatoes (Shelton 2015). Trissolcus basalis is attracted to host eggs over long distances by odors released from the eggs, while volatiles emanating from the host plant mediate short-range host location (Colazza et al. 2004). These semiochemicals enable T. basalis to locate and parasitize N. viridula and other stink bugs. Trissolcus basalis reproduces immediately after emerging from the host egg and the next generation of adults emerge 9-12 days after parasitization. Females can produce 230-300 eggs (Shelton 2015).

Trichopoda pennipes

Trichopoda pennipes is a parasitoid of many true bugs throughout the Southeast, including the southern green stink bug and the squash bug, Anasa tristis (De Geer) (Shelton

2015). It is found on squash and other vegetable crops that are infested by the southern green stink bug. Adult T. pennipes are attracted to the male pheromone of N. viridula that attracts conspecific females. Adult female T. pennipes are so strongly attracted to the N. viridula male pheromone that they track the host with little regard to the associated plant (Mitchell and Mau

1971). Thus, the pheromone acts as a kairomone with 43% parasitization of males and 32% of females (Harris and Todd 1980). Trichopoda pennipes overwinters in its host and emerges in late

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spring or early summer. The larvae of T. pennipes invade the tissue of its host and only one larva emerges. The larva enters the soil surface and emerges as an adult about two weeks later

(Shelton 2015). The females can produce hundreds of eggs.

Predators of Stink Bugs

Predators of stink bugs occur on a wide variety of vegetable crops and include lacewings and many ladybeetle species, such as the convergent lady beetle, Hippodamia convergens

(Guerin-Meneville), the seven-spotted lady beetle; Coccinella septempunctata L., the pink lady beetle; Coleomegilla maculata (De Geer), and the Asian lady beetle; Harmonia axyridis Pallas.

Stink bug predators that feed on the egg masses of stink bugs included are the big-eyed bug,

Geocoris punctipes (Say), and the insidious flower bug, Orius insidiosus (Say) (Mizell et al.

2008, Tillman 2008). The spined soldier bug, Podisus maculiventris (Say), also is a predator of nymphs of pest stink bug species (Tillman 2008). Many of the predators feed on various stages of stink bugs, ranging from eggs to nymphs and adults.

Figure 1-1. Left, adult southern green stink bug, Nezara viridula. Middle; N. viridula stink gland pore. Right, Chinavia halaris stink gland pore. Photograph and diagrams by James Castner, University of Florida.

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B

Figure 1-2. (A) Dorsal view of the brown stink bug. (B) Ventral view if a female brown stink bug. Photographs by W. Louis Tedders & Herb Pilcher, USDA, Bugwood.org.

Figure 1-3. (Right) Dorsal view of E. quadrator. (Left) Ventral view of E. quadrator. Confirmed by Joseph Eger. Photograph by Michael Grodowitz.

Figure 1-4. Three diagnostic features to distinguish between E. servus. Banding on the antennae, alternating bands on the margin of the abdomen, and no humeral spines. Photograph by Lyle J. Buss.

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Figure 1-5. Stink bug Dichelops furcatus feeding on wheat Triticum aestivum L. The stylet is penetrating the stem epidermis into the tissue. Ep is the stem epidermis and Pa is the parenchyma. Photographs by Tiago Lucini and Antonio R Panizzi, 2017.

Figure 1-6. Stink bug damage produced by adults and nymphs feeding on the tomato. The cloudy blotches are white to yellow in color and creates a spongy tissue underneath the epidermis. Photo by Gannon 2018.

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A SORGHUM TRAP CROP TO PREVENT STINK BUGS FROM INFESTNG ORGANIC TOMATOES

Introduction

Sorghum trap crops can attract stink bugs and reduce the damage that is caused to tomatoes if deployed effectively. Based on previous research (Mizell et al. 2008), planting three rows of sorghum between stink bug sources and a tomato crop would prevent a significant number of the pests from infesting the crop. However, a gap exists in understanding the process of stink bug colonization of cultivated plants. Stink bugs overwinter in uncultivated areas as diapausing adults, become active as photoperiod and temperature increases in the spring, aggregate and reproduce on field borders, infest crop plants eventually spreading rapidly into the field (Mitchell and Mau 1971, Todd 1989). The initial colonizing males emit a pheromone that attracts females and other males. The aggregation pheromone has been identified and is available commercially for some species of stink bugs. Moreover, the relative attractiveness of trap crops that can be planted in field borders to intercept colonizing males has been determined, though the optimum time to plant trap and vegetable crops is unknown (Mizell et al. 2008).

This research will determine the process by which stink bugs colonize sorghum and tomato plants so infestation of tomato crops can be reduced or prevented. The study will also provide an opportunity to monitor for parasitoids (tachinids) and predators (coreids and other pentatomids, such as, leaf-footed bugs, and the brown marmorated stink bug). Specific objectives for this study include the following: 1) determine the species of stink bugs and their abundance in sorghum and tomato, 2) the number of sorghum rows required to intercept stink bugs to prevent them from significantly damaging tomato, 3) define differences in tomato injury with or without sorghum, 4) determine the reproductive potential of female stink bugs on outer sorghum rows, and 5) the percentage of southern green stink bugs parasitized by Trichopoda pennipes.

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Materials and Methods

Site Description

The research was conducted in an irrigated 8.1 x 103 m certified organic vegetable production field at the UF/IFAS NFREC-SV, a 1.34 x 106 m research and extension demonstration farm located near Live Oak, Florida. The field was bordered on the east side by forestland and on the other three sides by well-established Bermudagrass and weeds (Fig. 2-1).

Approximately half of the field was set aside for research on organic carrot production and surrounded by rye that was mowed periodically. The remainder of the field was reserved for this research project.

Experimental Design

The study was conducted in a 42.7 by 8.2 m research plot in the organic vegetable field.

The experiment was a split-plot un-randomized design with three replicates. Whole plots represent tomatoes exposed to trap crops (sorghum), and tomatoes without trap crops (control).

Sections represent 3 stages of sorghum (oldest (A1, B1 and C1); younger (A2, B2 and C2), and youngest (A3, B3 and C3) (Fig. 2-2). Each section size is 6.1 m and a 3 m wide buffer was incorporated on the north and south sides of the organic field to reduce the weeds and alternate host for stink bugs. The plot has three rows of SP7715 sorghum (Sorghum Partners®, New Deal,

TX) planted in 0.76 m wide rows on the east and west sides (Fig. 2-2). Rows 1 and 8, 2 and 7, and 3 and 6 were planted on March 1, March 15 and April 1, respectively. The variety,

‘Granadero Organic’ (F1) tomato seedlings (Johnny’s Selected Seeds, Fairfield, Maine) were planted on April 16 in two, 1.83 m wide rows spaced 0.61 m apart down the center of the plot between the inside rows of sorghum. The tomato variety takes approximately 75 days to mature and produce fruit, in this case about the end of June. The tomatoes were a plum type that produced high yields, bright color, and was resistant to fusarium wilt, powdery mildew, tobacco

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mosaic virus, verticillium wilt, tomato spotted wilt virus, and nematodes. This resistance is necessary because only OMRI-approved pesticides can be sprayed in or near the plot.

A highly experienced farm crew at the research center performed all the agronomic best management practices for a certified organic plot. Tomato seeds were planted in a greenhouse using Burpee® Natural and Organic Seed Starting Mix (Warminster, PA). Nature’s Nectar

(Huntington, NY) phosphorus, potassium, and nitrogen was utilized based off the label rate in the greenhouse before transplanting. After the tomatoes were transplanted, they were staked, wired, and fenced in to provide stability and prevent animals from feeding. The rate of sorghum seed planted was 30,000 seed per 4047 m on a 762 mm row pattern. Chicken manure Everlizer®

(Organic Gowing Solutions LLC, Mayo, FL) was used for fertilizer and the plot was hand weeded when necessary. No herbicide, insecticide, or fungicides were used within the plot.

Overhead irrigation was used with data gathered from a soil moisture senor was to determine irrigation for tomatoes.

Stink Bug Collection

Scouting of stink bugs started on June 7, 2018, but collection used for analysis was on

June 21, 2018 (week 1) when the sorghum seed heads were at the milk stage. Stink bug collection ended on August 2, 2018 when the sorghum matured and the tomatoes were harvested, so seven weeks of data were derived. A maximum of 20 stink bugs were hand-collected from each section, (e.g. A-1, B-1, eg.) of every row on Thursdays of successive weeks. If the maximum was not available, all stink bugs in the section were collected. This was the maximum collected due to the limited amount of time available for two researchers in a day. Collections started on the north outside sorghum rows with sections A-1 and A-8 at 8:30 am, i.e., an observer moving down each row on the east and west ends of the plot. Each plant was observed for approximately 5 minutes and, if stink bugs were present, a longer collection time was required

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until the maximum amount of stink bugs was collected in the section. The stink bugs were collected from the sorghum panicle, leaves, and fruit of tomato plants and were then placed in

0.2 x 0.15 meter smart zip plastic bags (Quart, Ziploc®) in the field and the bags were labeled with Sharpie® fine tip markers according to the section and date. The plastic bags containing stink bugs from each section of the plot were brought to the IPM laboratory at the University of

Florida and identified to species, dissected to determine ovary development, and observed for parasitization.

Stink Bug Identification

Stink bugs collected each week were taken to the IPM laboratory at the University of

Florida and examined under a Dino-Lite® Premier Digital Microscope (Dino- Lite®, USB

Model) and each species was measured for sex, length, and width. The species were identified with a key to the “Hemiptera of U.S. Authors” (J. E. Eger unpublished). Stink bug adults and nymphs were identified to species or to genus for Thyanta spp. Voucher specimens were deposited at the Florida Department of Agriculture and Consumer Services, Division of Plant

Industry and verified by Dr. Susan Halbert.

The sex was determined based on differences in the genitalia between the male and female structures. Length of stink bugs was measured from the rostrum to the end of the genital segment. The width was measured from the ends of the left and right humeral spines (Fig. 2-3).

The average length and width of each male and female species was determined. Species gender was excluded from the results if specimens were not collected.

Four Most Abundant Stink Bug Species Collected on Sorghum and Tomato

Tomato Injury

Tomatoes were harvested from rows 4 and 5 for five weeks beginning on June 28, 2018 and ending on July 26. Tomatoes were harvested at the start of the breaker stage occured via the

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surface changing from green to yellow, pink, or red. This allowed the tomatoes to be harvested with reduced rot on ripening fruit. Fruit that did not have severe rot, environmental injuries, disease, and other pest damage were placed by section row into 7.6-liter Ziploc® freezer bags and taken to the IPM laboratory for grading. Tomatoes with severe injury would reduce the visibility of stink bug injury. A USDA grade scale was used based on the type of injury caused by the insects (USDA 2005). Marketable and unmarketable tomatoes were determined by the

USDA scale. Each tomato was weighed and the number of feeding sites, cloudy blotches and insect probing (where the stylet pierced the epidermis) sites were recorded. A dot was placed on each probing or injury site with a fine tip permanent marker (Sharpie®) so that no sites where missed or counted twice (Fig. 2-4). Each week, the tomatoes were graded and weighed, and the number of feeding sites was averaged separately for tomatoes from the treated and untreated sections.

Statistical Analysis

Stink bug counts

The mean numbers of the four predominant species of stink bugs collected each week were compared separately for the sorghum sections in each row. The weekly number of nymphs and adults of each species was averaged for the three replicates, e.g., sections A-1, B-1 and C-1 for row 1. Next, the mean numbers of stink bugs collected over all seven weeks in the three rows of sorghum were compared statistically. The number of each stink bug species from rows on the east side of the research plot (rows 1, 2, and 3) were compared separately from rows on the west side (rows 6, 7, and 8). Finally, all rows were compared for each week (rows 1, 2, 3, 6, 7, and 8) to determine if any difference occurred throughout the sorghum. The same procedure was followed for the stink bugs collected from tomato plants, except the insects from treated sections adjacent to sorghum plants were averaged separately from those collected from untreated

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sections. The mean numbers of stink bugs collected from treated and untreated sections were compared separately for the rows of tomato plants on the east and west sides. Then the mean numbers of each species of stink bug collected from treated and untreated sections over seven weeks were compared for both rows of tomato plants (i.e., mean of A-4 & 5, B-4 & 5, C-4 & 5 versus the mean of A-4T & 5T, B-4T & 5T, C-4T & 5T). All the statistical analysis was made using the GLIMMIX Procedure (SAS Version 9.3, SAS Institute, Inc., Cary, North Carolina).

Injury

Feeding damage on tomatoes from the treated and untreated east and west side of the field (rows 4 and 5) was analyzed separately. Then, the mean number of feeding sites were compared for all the treated versus untreated sections. The mean number of feeding sites were compared using the least squares mean with alpha <0.05 indicating no significant difference between treated and untreated tomatoes. Mean feeding sites for each week were plotted on a scatter plot and log transformed to represent the predicted change of the average feeding sites for each week. The Tukey-Kramer grouping for least squared means (α=0.05) analysis was used in the GLIMMIX Procedure (SAS Version 9.3, SAS Institute, Inc., Cary, North Carolina).

Stink Bug Reproductive Status

A maximum of 60 stink bugs were collected on the outside sorghum rows each week

(rows 1 and 8). In each outside sorghum row section, 10 of the most abundant female stink bugs collected each week (A-1, B-1, C-1, A-8, B-8, and C-8) were randomly selected for dissection in the IPM laboratory at the University of Florida. If there were not enough stink bugs to obtain the maximum of 60 for the outside rows each week, then all females that were collected in the outside rows were dissected. Stink bugs were placed in a dissecting dish under a Leica S8APO dissecting microscope (Wetzlar, Germany) and pinned through the pronotum with the ventral side up (Fig. 2-5). Dissecting scissors were used to cut across the first abdominal segment and

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then ventrally towards the genitalia. The abdominal cavity was held open by pulling the integument apart and pinning each side to the dissection dish. Ovary development was based on the amount of eggs: None, light (1-4), moderate (5-10), and heavy (10+) and were photographed with the digital microscope. The total mean of each category was measured for all seven weeks of the species collected. The total number of each female species dissected each week was recorded.

Stink Bug Parasitism

The adult stink bugs collected from the plot were inspected visually for external parasitoids. Parasitoid eggs were observed on some stink bugs when collected in the field or when examined under the microscope during species identification. The eggs were found throughout the external stink bug body but mostly located on the dorsal abdomen. Parasitized stink bugs were maintained in the laboratory until the parasitoids emerged. Stink bugs were placed in separate 3.79-liter, wide mouth jars with 0.05 x 0.05 x 0.04 meter Grodan® Rockwool

Cubes (Grodan, Inc., Roermond, The Netherlands) saturated with tap water, green beans, and peanuts. The host stink bugs were checked every 24 hours to determine if a parasitoid pupa emerged. Each parasitoid pupa was moved to an individual 6” x 3.25” plastic container (Betty

Crocker®, Golden Valley, Minnesota) and held until the adult emerged. The parasitoid adults were pinned and deposited at the Florida Department of Agriculture and Consumer Services,

Division of Plant Industry, verified by Dr. Gary Steck. Adult stink bugs that did not survive the trip to the laboratory were frozen and inspected for parasitoids when measured under the digital microscope. Eggs on the stink bugs were photographed and the occurrence was recorded each week. Due to the low number of parasitoids that emerged, the percentage of parasitism was based on the total number of eggs present on the host stink bugs. The total host species was determined each week and the percent parasitized was based on the weekly population.

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Figure 2-1. North Florida Research and Education Center- Suwannee Valley (research and demonstration farm) with organic field plot (red) in inset. Photo by Alexander Gannon, 2018.

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East Replicate A Replicate B Replicate C 3 + meter 6.1 meter 6.1 meter 6.1 meter 6.1 meter 6.1 meter 6.1 meter 3 + meter Buffer Trap crop No trap crop Trap crop No trap crop Trap crop No trap crop Buffer 0.76-m Oldest Oldest Oldest row 1 sorghum sorghum sorghum Plant A-1 B-1 C-1 3/1/18 0.76-m Younger Younger Younger row 2 sorghum sorghum sorghum Plant A-2 B-2 C-2 3/15/18 0.76-m Youngest Youngest Youngest row 3 sorghum sorghum sorghum Plant A-3 B-3 C-3 4/1/18 1.8-m Medium Medium size Medium size Medium size Medium Medium size row 4 size tomato tomato tomato tomato size tomato tomato Plant A-4 A-4 T B-4 B-4 T C-4 C-4 T 4/16/18 1.8-m Medium Medium size Medium size Medium size Medium Medium size row 5 size tomato tomato tomato tomato size tomato tomato Plant A-5 A-5 T B-5 B-5 T C-5 C-5 T 4/16/18 0.76-m Youngest Youngest Youngest row 6 sorghum sorghum sorghum Plant A-6 B-6 C-6 4/1/18 0.76-m Younger Younger Younger row 7 sorghum sorghum sorghum Plant A-7 B-7 C-7 3/15/18 0.76-m Oldest Oldest Oldest row 8 sorghum sorghum sorghum Plant A-8 B-8 C-8 3/1/18 West

Figure 2-2. Field plot experimental design with sorghum trap crop sections adjacent to the tomato crop (treated, T) or no trap crop (untreated)

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Figure 2-3. Width of N. viridula measured from the end of the left and right humeral spines. Photo by Alexander Gannon, 2018.

A B

Figure 2-4. Tomatoes from a section in a row (A) and marked with sharpie where damage occurred (B). Photo by Alexander Gannon, 2018.

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A

B

Figure 2-5. Heavy eggs present in N. viridula. A. Mature eggs. B. Expanded spermatheca. Photo by Alexander Gannon, 2018.

Figure 2-6. Parasitoid egg and length of male N. viridula. Photo by Alexander Gannon, 2018.

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CHAPTER 3 RESULTS AND DISCUSSION

Results

Stink Bug Species Collected on Sorghum and Tomato

Ten species of stink bugs were collected in the sorghum and tomato rows during the seven-week study (Table 2-1). Nezara viridula was the most abundant with 602 specimens.

Piezodorus guildinii was the second most captured with 514 specimens. The genus Euschistus had 110 specimens captured, 82 for E. servus and 28 for E. quadrator. The remainder of the six species captured were not as prevalent, with Thyanta spp. having 18 captured and Proxys punctulatus only having one specimen caught. No statistical analysis was used, as these results determined the common species being encountered and their abundance.

Stink Bug Measurements

The length and width of each species collected within the field were measured and the averages (+ SD) were recorded (Table 2-2). The two largest species with an average length for both males and females greater than 12 mm were N. viridula and E. servus. The smallest species in length under 10 mm were male P. guildinii, E. quadrator, and Thyanta spp. The species with a width greater than 7.70 mm were male and female N. viridula and E. servus and the species with a width under 6.0 mm were P. guildinii and Thyanta spp. The five species with three or fewer specimens were not included in the size comparisons.

Sex and Stage of the Four Most Abundant Stink Bug Species Collected Each Week on Sorghum and Tomato

The sex and stage were determined for the four most abundant stink bug species collected on sorghum and tomato (Table 2-3). In the first week of the study, three female N. viridula were collected on sorghum. In week 2, N. viridula increased with 29, 11 males and 18 females. In weeks 3, 4, and 5, this species increased in sorghum totaling 76, 140, and 167, respectively. In

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weeks 6 and 7, N. viridula decreased with a total of 96 and 28, respectively. There were 209 males and 300 females caught in sorghum over the seven weeks of the study.

In tomato, a total of 63 N. viridula were collected in 7 weeks. Week 1 had 21 N. viridula collected with more nymphs than adults. In weeks 2-5, 10 specimens of N. viridula were collected per week with more nymphs than adults. A decrease was observed in week 6 with only

2 N. viridula collected and none were collected in week seven.

Two female P. guildinii were collected on sorghum in week 1. In week 2, 144 P. guildinii were collected, 58 males and 86 females. Another increase occurred in week 3, with 193 collected and then the number decreased in week 4 to 130. There was a large decrease in P. guildinii at week 5 with 40 captured, followed with only one female captured in week 6 and none in week 7. There were only a few P. guildinii captured in tomato, with one male in week 2 and one female in week 5.

The genus Euschistus contained two species, E. servus and E. quadrator, with only four

E. servus collected in sorghum in week 1. The only E. quadrator found in sorghum was in week

2, being 1 female and 1 male, although 15 E. servus were captured. In weeks 3 and 4, 12 and 14

E. servus were captured, respectively, and the number decreased to 5, 4, and 0 in weeks 5, 6, and

7. In tomato, a total of 17 E. servus and E. quadrator were collected in week 1. In week 2, the combined species also totaled 17 but decreased in week 3 to 6 specimens. The capture of

Euschistus species decreased in weeks 4, 5, 6, and 7, with 4, 5, 4, and 0 specimens, respectively.

Significantly more N. viridula, P. guildinii and E. servus were collected from sorghum than tomato, whereas E. quadrator occurred most often in tomato.

Nezara viridula was the most abundant species of stink bug in the sorghum trap crop. The total number of N. viridula adults and nymphs was 539, 209 males and 300 females, plus 30

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nymphs. Nezara viridula was relatively less abundant in tomato with 63 specimens; 9 males, 24 females and 40 nymphs. Piezodorus guildinii was the next most abundant species of stink bug found in sorghum with a total of 510 collected. This pest had 250 males and 260 females but no nymphs in the field. Only 1 male and 1 female P. guildinii were collected in tomato, and no nymphs. Euschistus servus was the third most abundant stink bug species found on sorghum and second on tomato, with 54 and 27 specimens, respectively. The least abundant of the four species was Euschistus quadrator, with 2 on sorghum and 26 on tomato. Thus, N. viridula and P. guildinii were the predominant stink bug species on sorghum and N. viridula, E. servus, and E. quadrator were the major pests of tomato.

Weekly Occurrence of the Four Most Abundant Stink Bug Species in Each Row of Sorghum and Tomato

Nezara viridula in sorghum

The mean number of N. viridula captured in each row of the sorghum trap crop was recorded weekly (Table 2-4). There were no significant differences in the mean number of N. viridula collected in rows 1 through 3 on the east side and between rows 6 through 8 on the west side. The means for the six rows were combined and again there were no significant differences between rows each week. On both the east and west side of the field, significantly more stink bugs occurred in week 5. Nezara viridula infested the sorghum in week 1, steadily increased until week 5, and decreased until the sorghum reached senescence in week 7 (Figure 2-8).

Nezara viridula in tomato

Nezara viridula infested the treated and untreated tomato crops throughout the seven- week study (Table 2-5). There was no statistically significant difference in the occurrence of N. viridula between the east and west side of the plot, respectively rows 4 and 5. There also was no difference in the number of N. viridula between treated and untreated tomato sections (A-4 vs A-

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4T, etc.). Therefore, the mean numbers of N. viridula captured in the two tomato rows were combined for each week (Figure 2-9). The weekly average number of N. viridula captured in treated and untreated tomato each week peaked in week 1 and continuously decreased until the average was approximately 0 by week 7 (Figure 2-7).

Piezodorus guildinii in sorghum

Piezodorus guildinii occurrence was measured in the sorghum because only two specimens were encountered in tomato (Table 2-6). There was no statistically significant difference in the number of P. guildinii within the three east and within the three west rows per week, with the highest occurrence in week 3. There also was no significant difference in the number of P. guildinii in the east versus west rows of sorghum, so weekly means for all six rows were compared with the data for N. viridula (Figure 2-8). Piezodorus guildinii had a very low occurrence in week 1 and increased significantly by week 2. The occurrence of P. guildinii increased in week 2, peaked in week 3, and decreased in weeks 4-5. The pest was not present in weeks 6-7.

Euschistus servus in sorghum

Adult Euschistus servus occurred in both the sorghum and tomato. In sorghum, the number of E. servus in rows 1 through 3 on the east side of the field were not significantly different, with a peak occurrence at week 4 (Table 2-7). Similarly, the number of E. servus in the west rows 6-8 were not significantly different, with the highest average in week 2. The six rows were combined and there were no significant differences in the number of E. servus per week.

Due to a much lower total occurrence of E. servus than N. viridula and P. guildinii, in sorghum, data for E. servus was not included in Figure 2-8.

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Euschistus servus in tomato

In tomato, the average occurrence of E. servus was not significantly different between the east and west rows, four and five, respectively (Table 2-8). The weekly number of E. servus in treated and untreated tomato sections also was statistically equivalent. The average abundance of

E. servus was highest in week 1, slowly decreased until week 3, and remained relatively constant until week 6 (Figure 2-9).

Euschistus quadrator in tomato

Euschistus quadrator was present on tomatoes through seven weeks (Table 2-9). There was no significance in abundance of E. quadrator between the treated and untreated sections of rows on the east side of the plot and the equivalent sections on the west side. There also was no difference in the average number of E. quadrator in the two rows, so the weekly means were combined (Figure 2-9). Euschistus quadrator steadily decreased from week 1 to week 5, increased in week 6, and did not occur in week 7 when the tomatoes were harvested.

Tomato Damage by Stink Bug Species

The mean number of N. viridula, E. servus, and E. quadrator feeding sites on tomatoes was determined each week beginning in week 2 (Table 2-10). The number of feeding sites on tomatoes from treated and untreated sections were statistically equivalent in the first week

(Figure 2-10). The number of feeding sites increased from week 3 to 6 as the stink bug populations continued to expand. Overall, the tomatoes from untreated subplots had significantly more feeding sites (F= 22.34, df= 55; P=0.043). However, the tomato damage at harvest during any week exceeded the USDA marketing standards (total damage > 3/8 inch in diameter).

Egg Development in Nezara viridula, Piezodorus guildinii, and Euschistus servus

Female N. viridula, P. guildinii, and E. servus collected in the two outside sorghum rows

(1 and 8) each week were dissected to determine if their ovaries were active with eggs being

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produced (Table 2-11). No eggs were present in the first week for N. viridula but one female had expanded ovaries. In week 2, two females had expanded ovaries, one had light (1-4 eggs developed), and another had heavy egg (10+) development. In week 3, 10 females had egg development, 7 with light to heavy egg content. In weeks, 4-6, most of the females had heavy egg development. Ovaries were no longer producing eggs in week 7. The ovary and egg development categories were compared for all weeks (n=119) and more female N. viridula contained a heavy amount of eggs through the seven-week trial.

One Piezodorus guildinii female had expanded ovaries in week 1 but there was no egg development. In week 2, 11 females had expanded ovaries, 4 had light, 7 moderate and 2 heavy egg development. In week 3, 29 females had either expanded ovaries or egg development. There was a decrease in egg development in weeks 4-5 and none in weeks 6-7. For all ovary and egg development categories in weeks 1-7, there were significantly more P. guildinii females with expanded ovaries (n=76).

Euschistus servus was the last relatively abundant female stink bug species collected on sorghum that was dissected for ovary and egg development (n=15). The females had expanded ovaries in weeks 1, 2 and 4 with some heavy egg development in weeks 2-6.

Parasitism of Nezara viridula by Trichopoda pennipes

Nezara viridula parasitism was not found in the field until week 4, July 12, 2018 (Table

2-13). During this week, 5.16% or 8 out of the 155 N. viridula collected were parasitized. In week 5, 11.8% of these stink bugs were parasitized, 21 out of 178. The highest percentage of parasitism, 14.14%, occurred in week 6, but decreased to 3.57% in week 7. The mean percentage of N. viridula parasitized was 9.57% during the four weeks.

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Discussion

Stink Bug Abundance on Sorghum and Tomato

Of the ten species of stink bugs collected during this study, N. viridula, P. guildinii, E. servus, and E. quadrator were the most abundant. Only N. viridula, Chinavia hilaris, E. servus, and Oebalus pugnax have sorghum as a host (Guo et al. 2010). Tomato serves as a host crop for

N. viridula, E. servus, E. quadrator, and C. hilaris. As expected, N. viridula was the most prevalent species due to its attraction to both sorghum and tomato, and it had a higher female to male ratio in both crops. The mean number of N. viridula in tomato was relatively high at the beginning of the study but declined as the sorghum reached the most attractive stage. The remaining low number of adults in the tomato rows could have resulted in the non-significant difference in the infestation of treated and untreated tomato. In sorghum, the peak occurred in weeks 4 and 5 because the sorghum plants were at the preferred milk stage when the grain begins to form, and the kernel contains milky fluid (Mizell et al. 2008). Due to the small size of the plot, there was no significant difference in the occurrence of N. viridula in the east and west rows of sorghum. Nezara viridula was the only species that produced nymphs and about the same number were collected in the tomato and sorghum, indicating that reproduction occurred in both crops and reproductive potential was about the same (Orr and Boethel 1990). However, no egg masses were found in either crop.

Piezodorus guildinii was the second most abundant species on sorghum with no sex ratio bias regardless of crop but only two specimens were collected from tomato. This species increased sharply in week 2 and peaked in week 3. This sharp increase could have been due to the loss of the legume host on which they developed. Piezodorus guildinii occurs mainly on soybean, alfalfa and bean but there are no reports of this species on sorghum (Panizzi and

Slansky 1985). During our study, crops grown at NFREC-SV North Florida Research and

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Education Center- Suwannee Valley included corn, peanuts, sweet potatoes, and sorghum.

Interestingly, P. guildinii was not found on the peanuts. In week 4, there was a sharp decline, perhaps because the stink bugs were attracted to a suitable host crop. Alternatively, N. viridula could have displaced the less competitive P. guildinii. In Brazil, Euschistus heros (F.) competed with P. guildinii in soybean but the mechanism of competition in the study was not determined

(Tuelher et al. 2016). Euschistus servus and Euschistus quadrator were the third and fourth most prevalent species, respectively, collected during the study.

Stink Bug Injury to Tomato

Nezara viridula was clearly the most prevalent stink bug species in tomatoes that caused most of the damage throughout the season, however E. servus and E. quadrator also were present and probably feeding. Although sorghum-treated tomatoes had significantly fewer feeding sites, the injury rendered to both treated and untreated tomatoes were unmarketable.

These species were present in the tomato rows causing injury in week 1 but could have become much more abundant if not attracted to the sorghum. However, even at low densities, stink bugs can cause high amounts of tomato damage. Two N. viridula can probe and deposit an average of

122.4 stylet sheaths in a 9-day feeding period (Lye et al. 1988).

Stink Bug Measurements

Measurements of the length and width of the 10 stink bug species collected in this study agreed with published descriptions (McPherson and McPherson 2000). Chinavia halaris females were the largest, known to range in length 14 to 19 mm (Gomez and Mizell 2008). Nezara viridula males were the largest, averaging 13.4 mm, whereas the reported length is 12.1 mm

(Squitier 2013). Female stink bugs are larger than males ostensibly because of egg development.

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Evaluation of the Study

The results of this study could have been affected by plot size, experimental design, synchronization of the sorghum and tomato plant phenology, agronomic requirements for the organic crops, stink bug collection methods, and other variables. A larger plot size would disperse the population of stink bugs instead of concentrating them into a small area. Timing of sorghum and tomato planting can impact the distribution of stink bugs. If tomatoes are present before the milk stage of sorghum, stink bugs will colonize tomato instead of sorghum. Sorghum seed heads were not present in week 1, possibly causing stink bugs to disperse into the tomato rather than sorghum rows. The study could have been improved by using two plots, one with and the other without sorghum. The sorghum might be more effective on a larger scale with an increase in row spacing. Sorghum could be more effective if planted earlier in the season but can be affected by frost and cooler temperatures. The study was conducted on certified organic land that required organic fertilizer and hand weeding, which could have delayed the growth of the crops and disrupt the timing of attractiveness of sorghum. Hand collecting the stink bugs on tomatoes and the time of day when collections were made could have limited the number of stink bugs captured. Placing a white piece of plastic or fabric under the tomato plants could facilitate catching adults and nymphs that fall off the plant. Collecting twice a week would increase the number of stink bugs captured. These collection improvements could increase the sampling precision and provide a more accurate estimate of the stink bugs within the field.

Conclusion

The seven-week field study achieved some of the objectives and created new questions that can be addressed in the future. The species and abundance of stink bugs in the sorghum and tomato crops were determined. However, the number of sorghum rows required to prevent stink bugs from damaging the tomatoes was not established. Stink bugs were present in all three rows

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of sorghum and two rows of tomato. Differences in stink bug species abundance and damage were evaluated between tomatoes adjacent to sorghum and without sorghum. The condition of ovaries and egg development indicated the reproductive status of the stink bug females collected in the field. Finally, the weekly number of southern green stink bugs parasitized by T. pennipes was recorded.

Organic tomato production will continue to increase throughout the Southeast as consumers purchase more organic products. Integrated pest management strategies will be crucial for reducing pest damage and associated economic losses in organic agriculture, such as trap cropping, scouting and monitoring, biopesticides for pest and diseases, biological control, and various preventative measures. A better understanding of the potential effectiveness of

Trichopoda pennipes might lead to its mass rearing and release during the tomato growing season to reduce Nezara viridula populations. In our study, parasitism did not begin until week 4, which limited the impact of this natural enemy for biological control of N. viridula on tomatoes.

This delay in parasitism allowed the N. viridula population to increase and damage the tomatoes.

This kind of research also can lead to studies on organic pesticides that can reduce pest pressure.

Conducting pesticide efficacy trials on stink bugs and other pests can assist organic farmers and give them more options to protect their crops. Incorporating a trap crop with organic pesticides might decrease the amount of total pesticide use on the cash crop. Finding ways to implement each IPM strategy: preventative, cultural, biological, and chemical will enable organic tomato farmers to reduce the damage caused by stink bugs and increase crop yield and profitability.

Educating farmers about these practices and continuous research on different methods for reducing pest damage below the economic threshold is crucial for the future.

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Table 3-1. Total number of stink bug species collected during the study. Stink bug species Common name1 Total collected Nezara viridula (Linnaeus) Southern green stink bug 602 Piezodorus guildinii (Westwood) Redbanded stink bug 514 Eushistus servus (Say) Brown stink bug 82 Eushistus quadrator (Rolston) (Lesser brown stink bug) 28 Thyanta spp. Redshouldered stink bug 18 Euschistus tristigmus (Say) Dusky stink bug 4 Eushistus ictericus (Linnaeus) (Shield bug) 3 Oebalus pugnax (Fabricius) Rice stink bug 2 Chinavia hilare (Say) Green stink bug 2 Proxys punctulatus (Palisot) (Black stink bug) 1 1Stink bug common names in parenthesis are not ESA approved.

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Table 3-2. Mean (+SD) length and width (in millimeters) of all male and female stink bugs of each species collected in sorghum and tomato. Species Sex Length Width Total Nezara viridula Male 13.38+ 7.70+ 219 0.46 0.16 Female 15.22+ 8.38+ 324 1.08 0.57 Piezodorus guildinii Male 9.53+ 5.45+ 253 0.16 0.10 Female 10.51+ 5.84+ 262 0.26 0.21 Eushistus servus Male 12.10+ 7.85+ 43 0.39 0.18 Female 12.89+ 8.29+ 56 0.46 0.37 Eushistus quadrator Male 9.26+ 6.09+ 29 0.22 0.33 Female 9.86+ 6.60+ 26 0.32 0.19 Thyanta spp. Male 9.16+ 5.68+ 8 0.35 0.24 Female 10.07+ 5.93+ 11 0.63 0.27 Euschistus tristigmus Male ------

Female 11.48+ 8.43+ 3 0.70 0.15 Eushistus ictericus Male 11.74+ 7.74+ 3 0.06 0.23 Female ------

Oebalus pugnax Male 8.86+ 4.24+ 2 0.23 0.23 Female ------

Chinavia hilare Male ------

Female 15.89+ 9.37+ 2 0.98 0.68 Proxus punctulatus Male ------

Female 11.95+ 7.08+ 1 0 0

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Table 3-3. Total number of male, female and nymph stink bugs of the four most common species collected on all rows of sorghum and tomato during each week of the study. Sorghum Tomato Week Male Female Nymph Total Male Female Nymph Total Nezara viridula 1 0 3 0 3 0 6 15 21 2 11 18 0 29 3 3 4 10 3 28 46 2 76 1 3 6 10 4 54 80 6 140 3 0 7 10 5 66 89 12 167 1 1 8 10 6 43 50 3 96 1 1 0 2 7 7 14 7 28 0 0 0 0 Total 209 300 30 539 9 14 40 63 Piezodorus guildinii Week Male Female Nymph Total Male Female Nymph Total 1 0 2 0 2 0 0 0 0 2 58 86 0 144 1 0 0 1 3 106 87 0 193 0 0 0 0 4 67 63 0 130 0 0 0 0 5 19 21 0 40 0 1 0 1 6 0 1 0 1 0 0 0 0 7 0 0 0 0 0 0 0 0 Total 250 260 0 510 1 1 0 2 Euschistus servus Week Male Female Nymph Total Male Female Nymph Total 1 1 3 0 4 5 4 0 9 2 3 12 0 15 5 2 0 7 3 4 8 0 12 2 1 0 3 4 6 8 0 14 3 0 0 3 5 1 4 0 5 2 2 0 4 6 1 3 0 4 0 1 0 1 7 0 0 0 0 0 0 0 0 Total 16 38 0 54 17 10 0 27 Euschistus quadrator Week Male Female Nymph Total Male Female Nymph Total 1 0 0 0 0 4 4 0 8 2 1 1 0 2 4 6 0 10 3 0 0 0 0 1 2 0 3 4 0 0 0 0 0 1 0 1 5 0 0 0 0 1 0 0 1 6 0 0 0 0 0 3 0 3 7 0 0 0 0 0 0 0 0 Total 1 1 0 2 10 16 0 26

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Table 3-4. Mean (+SD) number of Nezara viridula collected in each row and week in the sorghum trap crop. Week

1 2 3 4 5 6 7 Row Sorghum (east) 0 0.33+ 3.33+ 8+ 14+ 6+ 0 1 0.58 3.06 1.73 3.61 7.00 0.67+ 1.67+ 5.33+ 5.67+ 3.67+ 3+ 0 2 0.58 2.89 1.53 2.52 2.08 1.73 0 0.33+ 4.33+ 5.67+ 7+ 3.33+ 2.67+ 3 0.58 2.31 1.15 5.57 4.93 2.89 0.22+ 0.78+ 4.33+ 6.45+ 8.22+ 4.11+ 0.89+ X+SD 0.39 0.77 1.00 1.35 5.27 1.65 1.54

Sorghum (west) 3.67+ 4.33+ 10+ 10+ 5.67+ 3.67+ 6 0 3.06 1.15 0 2.65 4.73 2.08 1+ 4.67+ 6.33+ 7+ 4+ 1+ 7 0 1.73 4.51 1.15 3.46 3 1 0.33+ 2.67+ 3+ 11+ 14+ 10+ 2+ 8 0.58 3.06 3 6.08 7.55 4.58 1.73 0.11+ 2.45+ 4+ 9.11+ 10.33+ 6.56+ 2.22+ X+SD 0.19 1.35 0.88 2.46 3.51 3.10 1.35 1-3+ 6-8 0.17+ 1.61+ 4.17+ 7.78+ 9.28+ 5.33+ 1.56+ X +SD 0.28 1.34 0.86 2.30 4.17 2.59 1.49 p-value 0.179 0.650 0.915 0.161 0.088 0.490 0.101 1p-values are comparing average number of N. viridula by all rows for each week.

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Table 3-5. Mean (+SD) number of Nezara viridula collected each week in treated and untreated rows of tomatoes. P-value was determined by combining treated and untreated tomato each week.

Week

Rows 1 2 3 4 5 6 7

Tomato (treated) 0.67+ 0.33+ 2+ 1.67+ 0.33+ 0.33+ 0 4 0.58 0.58 1.73 1.53 0.58 0.58 3.33+ 1+ 0.33+ 0.33+ 0.67+ 0 0 5 4.16 1.73 0.58 0.58 1.15 2+ 0.67+ 1.17+ 1+ 0.5+ 0.17+ 0 X+ SD 1.89 0.47 1.18 0.94 0.24 0.24

Tomato (untreated) 1+ 0.67+ 0 0.67+ 1.33+ 0 0 4 1 1.15 1.15 0.58 2+ 1.33+ 1+ 0.67+ 1+ 0.33+ 0 5 1 2.31 0 0.58 1 0.58 1.5+ 1+ 0.5+ 0.67+ 1.17+ 0.17+ 0 X+ SD 0 0.47 0.71 0 0.24 0.24 X + SD 1.75+ 0.83+ 0.83+ 0.83+ 0.83+ 0.17+ 0 (all rows) 1.20 0.43 0.88 0.58 0.43 0.19 p-value 0.507 0.659 0.109 0.473 0.557 0.596 NA

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2 1.8 1.6

1.4 N. viridulaN. 1.2 1 0.8 0.6 0.4

Average number of number Average 0.2 0 0 1 2 3 4 5 6 7 8 Week

Treated tomato Untreated tomato Log. (Treated tomato) Log. (Untreated tomato)

Figure 3-1. The mean number of Nezara viridula in treated and untreated tomato sections through seven weeks.

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Table 3-6. Mean (+ SD) number of Piezodorus guildinii collected each week and row in the sorghum trap crop.

Week Row 1 2 3 4 5 6 7

Sorghum (east) 0.33+ 8+ 14+ 9+ 2.33+ 1 0 0 0.58 2.00 0 2.65 1.53 8.33+ 7.67+ 6.33+ 3+ 2 0 0 0 4.73 2.08 1.53 3.46 0.33+ 5.67+ 12.67+ 8.33+ 3+ 3 0 0 0.58 8.14 4.16 1.15 1,00 0.22+ 7.33+ 11.45+ 7.89+ 2.78+ X+SD 0 0 0.19 1.45 3.34 1.39 0.39 Sorghum (west) 12.68+ 12.67+ 9.33+ 2.33+ 6 0 0 0 10.41 3.79 1.53 2.31 7+ 7.67+ 4.33+ 7 0 1 0 0 7.00 4.04 1.53 6.67+ 10.33+ 6+ 1.68+ 8 0 0 0 6.51 7.09 2 2.89 8.78+ 10.22+ 6.55+ 1.67+ X+SD 0 0 0 3.38 2.50 2.55 0.67 X +SD 0.11+ 8.06+ 10.83+ 7.22+ 2.22+ 0 0 (all rows) 0.17 2.45 2.72 1.97 0.78 rows) p-value 0.571 0.859 0.327 0.070 0.863 N/A N/A 1p-values are comparing average number of P. guildinii by all rows for each week.

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16

14

12

10

8

6

4

2 Mean number in bugs number sorghum stink Mean of 0 0 1 2 3 4 5 6 7 8 Week Piezodorus guildinii Nezara viridula

Figure 3-2. Mean (+SD) number of Piezodorus guildinii and Nezara viridula captured in sorghum rows 1-3 plus 6-8.

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Table 3-7. Mean (+SD) number of Euschistus servus collected in each row and week in the sorghum trap crop.

Week

Row 1 2 3 4 5 6 7 Sorghum (east) 0.67+ 1.33+ 0.67+ 0.67+ 1 1 0 0 0.58 1.53 0.58 1.15 0.33+ 0.33+ 0.33+ 0.33+ 0.67+ 2 0 0 0.58 0.58 0.58 0.58 1.15 0.33+ 0.33+ 1+ 0.33+ 0+ 3 0 0 0.58 0.58 1 0.58 0 0.33+ 0.44+ 0.22+ 0.89+ 0.44+ 0.44+ X+SD 0 0.58 0.19 0.19 0.51 0.19 0.38 Sorghum (west)

0+ 1.67+ 1.33+ 1.33+ 0.67+ 6 0 0 0 1.15 2.31 2.31 0.58 0+ 1.33+ 0.33+ 0.33+ 0+ 7 0 0 0 1.53 0.58 0.58 0 0.33+ 0.67+ 1.67+ 0.33+ 0+ 8 0 0 0.58 0.58 2.89 0.58 0 0.11+ 1.22+ 1.11+ 0.67+ 0.22+ X+SD 0 0 0.19 0.51 0.69 0.58 0.38 X+SD 0.22+ 0.83+ 0.67+ 0.78+ 0.33+ 0.22+ 0 (all rows) 0.55 0.92 1.96 1.17 0.49 0.65 p-value 0.122 0.419 0.739 0.792 0.366 0.571 NA 1p-values are comparing average number of E. servus by all rows for each week.

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Table 3-8. Mean (+SD) number of Euschistus servus collected in each row and week in the treated and untreated tomato crop. Week

Row 1 2 3 4 5 6 7

Tomato (treated) 1+ 1.33+ 0.33+ 0.33+ 0.33+ 0 0 4 1 2.31 0.58 0.58 0.58 0.33+ 0 0 0.33+ 0.33+ 0 0 5 0.58 0.58 0.58 0.67+ 0.67+ 0.17+ 0.33+ 0.33+ 0 0 X+SD 0.47 0.94 0.24 0 0 Tomato (untreated) 1 0 0 0 0.33+ 0 0 4 0.58 0.67+ 1+ 0.67+ 0.33+ 0.33+ 0.33+ 0 5 1.15 0 0.58 0.58 0.58 0.58 0.83+ 0.50+ 0.33+ 0.17+ 0.33+ 0.17+ 0 X+SD 0.24 0.71 0.47 0.24 0 0.24 X + SD 0.75+ 0.58+ 0.25+ 0.25+ 0.33+ 0.08+ 0 (all rows) 0.32 0.69 0.32 0.17 0 0.17 p-value 0.802 0.417 0.219 0.802 1.00 0.441 NA

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Table 3-9. Mean (+SD) number of Euschistus quadrator collected in each row and week in the treated and untreated tomato crop.

Week Row 1 2 3 4 5 6 7

Tomato (treated) 0.67+ 0.33+ 0.33+ 4 1 0 0 0 0.58 0.58 0.58 0.33+ 1+ 0.33+ 0+ 0.67+ 5 0 0 0.58 1 0.58 0 1.15 0.67+ 0.83+ 0.33+ 0.17+ 0.33+ X+SD 0 0 0.47 0.24 0 0.24 0.47 Tomato (untreated) 0.67+ 1.33+ 0.33+ 4 0 0 0 0 1.15 0.58 0.58 0.67+ 0.33+ 0.33+ 0.33+ 5 0 0 0 1.15 0.58 0.58 0.58 0.67+ 0.83+ 0.17+ 0.17+ 0.17+ X+SD 0 0 0 0.71 0.24 0.24 0.24 X + SD 0.67+ 0.58+ 0.25+ 0.08+ 0.08+ 0.25+ 0 (all rows) 0.27 0.57 0.17 0.17 0.17 0.32

p-value 0.878 0.400 0.802 0.441 0.441 0.561 NA

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2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4

Mean number bugs stink number of Mean 0.2 0 0 1 2 3 4 5 6 7 8 Week

Nezara viridula Euschistus servus Euschistus quadrator

Figure 3-3. The mean (+SD) number of Nezara viridula, Euschistus servus, and Euchistus quadrator in combined treated and untreated tomato subplots per week.

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Table 3-10. Mean (+SD) number of Nezara viridula, Eushistus servus, and Euschistus quadrator feeding sites on tomato each week. Week

Row 2 3 4 5 6

Treated X+SD

4 49.75+ 103.66+ 143.07+ 199.25+ 234.21+ 145.99+ 11.67 44.53 30.95 49.74 70.00 73.62 5 43.2+ 120.18+ 205.24+ 185+ 188.90+ 148.50+ 13.86 42.52 60.50 32.97 70.38 67.22 X+SD 46.48+ 111.92+ 174.16+ 192.13+ 211.56+ 147.25+ 4.63 11.68 43.96 10.08 32.04 67.60

Untreated X+SD

44.11+ 165.46+ 199.11+ 239.22+ 269.92+ 183.56+ 4 3.66 40.35 53.84 31.53 82.48 87.42 29+ 128.36+ 225.75+ 244.67+ 194.3+ 164.42+ 5 0 61.21 56.36 68.69 38.24 87.65 36.56+ 146.91+ 212.43+ 241.95+ 232.11+ 173.99+ X+SD 10.68 26.23 18.84 3.85 53.47 85.29

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Stink Bug Feeding Sites 300 250 200 150 100 50 0 1 2 3 4 5 6 7 Weeks

Average # of Feeding Sites per tomato tomato per Sites Feeding of # Average Treated Untreated Log. (Treated) Log. (Untreated)

Figure 3-4. Mean (+SD) number of feeding sites each week on treated and untreated tomatoes.

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Table 3-11. Mean (+ SD) ovary development and egg content for Nezara viridula, Piezodorus guildinii, and Euschistus servus females collected each week in the first and eighth rows of sorghum. Nezara viridula No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 1 0 0 0 1 2 2 1 0 1 4 3 3 1 1 5 10 4 4 3 4 21 32 5 9 6 7 21 43 6 5 1 4 15 25 7 2 0 0 2 4 3.71 + 1.71 + 2.29 + 9.29 + Mean +SD 119 2.69 2.14 2.75 9.43 Piezodorus guildinii No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 0 0 0 0 0 2 11 4 7 2 24 3 11 4 4 10 29 4 7 3 4 2 16 5 5 0 0 2 7 6 0 0 0 0 0 7 0 0 0 0 0 4.86 + 1.57 + 2.14 + 2.29 + Mean +SD 76 5.01 1.99 2.85 3.55 Euschistus servus No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 2 0 1 0 3 2 1 1 0 1 3 3 0 0 2 2 4 4 1 0 0 1 2 5 0 0 0 2 2 6 0 0 0 1 1 7 0 0 0 0 0 1.33+ 1.5+ 1.4+ Mean +SD 0 15 0.58 0.71 0.55

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Table 3-12. Ovary development and egg content for Nezara viridula, Euschistus servus and Euschistus quadrator females collected each week in the rows of tomato. Nezara viridula No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 3 0 0 2 5 2 0 1 0 2 3 3 1 0 0 1 2 4 0 0 0 0 0 5 0 0 0 1 1 6 0 0 0 0 0 7 0 0 0 0 0 Mean +SD 0.57 + 1.13 0.14 + 0.38 0 + 0 0.86 + 0.90 1.57 + 1.90

Euschistus servus No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 1 0 0 3 4 2 0 0 1 1 2 3 0 0 0 0 1 4 0 0 0 0 0 5 0 1 1 0 2 6 0 0 0 0 0 7 0 0 0 0 0 Mean +SD 0.14 + 0.38 0.14 + 0.38 0.29 + 0.49 0.57 + 1.13 1.29 + 1.50 Euschistus quadrator No egg Light egg Moderate egg Heavy egg Week Total content content content content 1 0 0 1 1 2 2 2 0 1 3 6 3 0 0 0 0 0 4 0 0 0 1 1 5 0 0 0 0 0 6 0 0 1 2 3 7 0 0 0 0 0 Mean +SD 0.29 + 0.76 0 + 0 0.43 + 0.53 1 + 1.15 1.71 + 2.21

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Table 3-13. The percentage of Nezara viridula parasitized by Trichopoda pennipes each week in both sorghum and tomato. Collected Parasitized Week (n) (n) (%) 4 155 8 5.16 5 178 21 11.80 6 99 14 14.14 7 28 1 3.57 Mean 460 44 9.57

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LIST OF REFERENCES

Balusu, R., E. Rhodes, O. Liburd, and H. Fadamiro. 2015. Management of yellowmargined leaf beetle, Microtheca ochroloma (Coleoptera: Chrysomelidae) using turnip as a trap crop. J. Econ. Entomol. 6: 2691-2701.

Blackman, B., C. Allen, W. Jones, N. Little, M. Grodowitz, and R. Luttrell. 2017. First report of the soybean pest Euschistus quadrator (Hemiptera: Pentatomidae) in Mississippi. Florida. Entomol. 100: 192-194.

Brennan, S. A., J. E. Eger, and O. E. Liburd. 2012. A stink bug, Euschistus quadrator Rolston (Insecta: Hemiptera: Pentatomidae). Featrued Creatures. UF/IFAS Extension.

Brumfield, R. G., F.E. Adelaja, and S. Reiners. 1993. Economic analysis of three tomato production systems. Acta Hortic. 340: 255-260.

Colazza, S., J. S. McElfresh, and J. G. Millar. 2004. Identification of volatile synomones, induced by Nezara viridula feeding and oviposition on bean spp., that attract the egg parasitoid: Trissolcus basalis. J. Chem. Ecol. 30: 945-964.

Cullen, E. M., and F. G. Zalom. 2000. Phenology-based field monitoring for consperse stink bug (Hemiptera: Pentatomidae) in processing tomatoes. Environ. Entomol.. 29: 560–567.

FDACS. 2015. Florida agriculture overview and statistics. (https://www.freshfromflorida.com/Agriculture-Industry/Florida-Agriculture-Overview- and-Statistics)

Gomez, C., and R. F. Mizell. 2008. Green stink bug, Chinavia halaris (Say) (Insecta: Hemiptera: Pentatomidae). Featured Creatures. UF/IFAS Extension.

Gordon, C., R. F. Mizell, and A. C. Hodges. 2008. Brown stink bug, Euschistus servus Say (Insecta: Hemiptera: Pentatomidae). Featured Creatures. UF/IFAS Extension.

Gordon, T. L., M., Haseeb, L. H. B., Kanga, and J. C. Legaspi. 2017. Potential of three trap crops in managing Nezara viridula (Hemiptera: Pentatomidae) on tomatoes in Florida. J. Econ. Entomol. 110: 2478-2482.

Guo, C., W. Cui, X. Feng, J. Zhao, and G. Lu. 2010. Sorghum insect problems and management. J. Integr. Plant. Biol. 53: 178-192.

Harris, V. E., and J. W. Todd. 1980. Male-mediated aggregation of male, female and 5th-instar southern green stink bugs and concomitant attraction of a tachinid parasite, Trichopoda pennipes. Entomol. Exp. Appl. 27: 117-126.

65

Herbert, J. J., and M. D. Toews. 2012. Seasonal abundance and population structure of Chinavia hilaris and Nezara viridula (Hemiptera: Pentatomidae) in Georgia farmscapes containing corn, cotton, peanut, and soybean. Ann. Entomol. Soc. Am. 4: 582-591.

Hokkanen, H. M. T. 1991. Trap cropping in pest management. Annu. Rev. Entomol. 36: 119- 138.

Jeram, S., and M. Pabst. 1996. Johnston's organ and central organ in Nezara viridula (L) (Heteroptera, Pentatomidae). Tissue. Cell. 28: 227-35.

Jones, W. A., and M. J. Sullivan. 1982. Role of host plants in population dynamics of stink bug pests of soybean in South Carolina. Environ. Entomol. 11: 867–875.

Leppla, N. C., M. W. Johnson, J. L. Merritt, and F. G. Zalom. 2017. Sustainable management of arthropod pests of tomato: applications and trends in commercial biological control for arthropod pests of tomato, 1st ed. Elsevier Inc, Linn, MO.

Leskey, T. C., and A. L. Nielsen. 2018. Impact of the invasive brown marmorated stink bug in North America and Europe: history, biology, ecology, and management. Annu. Rev. Entomol. 63: 599-618.

Lye, B. H., and R. N. Story. 1988. Feeding preference of the southern green stink bug (Hemiptera: Pentatomidae) on tomato fruit. J. Econ. Entomol. 81: 522-526.

Lye, B. H., R. N. Story, and V. L. Wright. 1988. Southern green stink bug (Hemiptera: Pentatomidae) damage to fresh market tomatoes. J. Econ. Entomol. 8: 189-194.

Macilwain, C. 2004. Organic: is it the future of farming? Nature. 428: 792-795.

McPherson, J. E., and R. McPherson. 2000. Stink bugs of economic importance in America north of Mexico. CRC Press LLC, Boca Raton, FL.

Mitchell, W., and R. F. L. Mau. 1971. Response of the female southern green stink bug and its parasite, Trichopoda pennipes, to male stink bug pheromones. J. Econ. Entomol. 64: 856- 859.

Mizell, R. F. 2005. Stink bugs and leaffooted bugs are important fruit, nut, seed, and vegetable pests. UF/IFAS Extension. http://edis.ifas.ufl.edu/in534

Mizell, R. F., T. C. Riddle, and A. S. Blount. 2008. Trap cropping system to suppress stink bugs in the southern coastal plain. Proc. Fla. State. Hort. Soc. 121: 377–382.

Musolin, D. L. 2012. Surviving winter: diapause syndrome in the southern green stink bug Nezara viridula in the laboratory, in the field, and under climate change conditions. Physiol. Entomol. 37: 309-322.

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Musolin, D. L., and H. Numata. 2003. Photoperiodic and temperature control of diapause induction and colour change in the southern green stink bug Nezara viridula. Physiol. Entomol. 28: 65–74.

Nault, B. A., and J. Speese. 2002. Major insect pests and economics of fresh-market tomato in eastern Virginia. Crop. Prot. 5: 359-366.

Nguyen, T., A. Wysocki, D. Treadwell, D. Farnsworth, and J. Clark. 2015. Economics of the organic food industry in Florida 1 organics — defined structure of Florida organic farms. UF/IFAS Extension. https://edis.ifas.ufl.edu/fe732.

Orr, D.B., and D.J. Boethel. 1990. Reproductive potential of Telenomus cristatus and T. podisi (Hymenoptera: Scelionidae), two egg parasitoids of pentatomids (Heteroptera). Ann. Entomol. Soc. Am. 83: 902-905.

Panizzi, A. R., and F. Slansky. 1985. Review of phytophagous pentatomids (Hemiptera: Pentatomidae) associated with soybean in the Americas. Florida. Entomol. 68: 184-214.

Penca, C. 2018. The brown marmorated stink bug, now a pest of limited distribution in Florida. (http://blogs.ifas.ufl.edu/pestalert/2018/09/03/bmsb_florida/)

Penca, C., and A. C. Hodges. 2019. Brown marmorated stink bug, Halyomorpha halys Stal (Insecta: Hemiptera: Pentatomidae). Featured Creatures. UF/IFAS Extension.

Pilkay, G. L., F. P. F. Reay-Jones, and J. K. Greene. 2013. Harmonic radar tagging for tracking movement of Nezara viridula (Hemiptera: Pentatomidae). Environ. Entomol. 42: 1020–1026.

Rea, J. H., S. D. Wratten, R. Sedcole, P. J. Cameron, S. I. Davis, and R. B. Chapman. 2002. Trap cropping to manage green vegetable bug Nezara viridula (L.) (Heteroptera: Pentatomidae) in sweet corn in New Zealand. Agric. For. Entomol. 4: 101–107.

Reay-Jones, F. P. F. 2010. Spatial and temporal patterns of stink bugs (Hemiptera: Pentatomidae) in wheat. Environ. Entomol. 39: 944–955.

Rice, K. B., C. J. Bergh, E. J. Bergmann, D. J. Biddinger, C. Dieckhoff, G. Dively, H. Fraser, T. Gariepy, G. Hamilton, T. Haye, A. Herbert, K. Hoelmer, C. R. Hooks, A. Jones, G. Krawczyk, T. Kuhar, H. Martinson, W. Mitchell, A. L. Nielsen, D. G. Pfeiffer, M. J. Raupp, C. Rodriguez-Saona, P. Shearer, P. Shrewsbury, P. D. Venugopal, J. Whalen, N. G. Wiman, T. C. Leskey, and J. F. Tooker. 2014. Biology, ecology, and management of brown marmorated stink bug (Hemiptera: Pentatomidae). J. Integr. Pest. Manag. 5: A1-A13.

Riahi, A., C. Hdider, M. Sanaa, N. Tarchoun, M.B. Kheder, and I. Guezal. 2009. Effect of conventional and organic production systems on the yield and quality of field tomato cultivars grown in Tunisia. J. Sci. Food Agric. 89: 2275-2282.

67

Rudd, W. G., and R. L. Jensen. 1977. Sweep net and ground cloth sampling for insects in soybeans. J. Econ. Entomol. 70: 301-304.

Shelton, A. 2015. Biological control: Trissolcus basalis. (https://biocontrol.entomology.cornell.edu/parasitoids/trissolcus.php%0A)

Shelton, A. 2015. Biological control: Trichopoda pennipes. (https://biocontrol.entomology.cornell.edu/parasitoids/trichopoda.php)

Shelton, A. M., and F. R. Badenes-Perez. 2006. Concepts and applications of trap cropping in pest management. Annu. Rev. Entomol. 51: 285-308.

Squitier, J. M. 2013. Southern green stink bug, Nezara viridula (Linnaeus) (Insecta: Hemiptera: Pentatomidae). Featured Creatures. UF/IFAS Extension.

Stivers, A. 2012. Trap crops for leaffooted bug management in tomatoes. Journal of the NACAA. 5.

Tillman, P. G. 2006. Sorghum as a trap crop for Nezara viridula L . (Heteroptera : Pentatomidae) in cotton in the southern United States. Environ. Entomol. 35: 771-783.

Tillman, P. G., J. R. Aldrich, A. Khrimian, and T. E. Cottrell. 2010. Pheromone attraction and cross-attraction of Nezara, Acrosternum, and Euschistus spp. stink bugs (Heteroptera: Pentatomidae) in the field. Environ. Entomol. 39: 610-617.

Tillman, P. G., A. Khrimian, T. E. Cottrell, X. Lou, R. F. Mizell, and C. J. Johnson. 2015. Trap cropping systems and a physical barrier for suppression of stink bugs (Hemiptera: Pentatomidae) in cotton. Ann. Entomol. Soc. Am. 108: 2324-2334.

Todd, J. W. 1989. Ecology and behavior of Nezara viridula. Annu. Rev. Entomol. 34: 82-87.

Treadwell, D. and J. Perez. 2017. Introduction to organic crop production. UF/IFAS Extension. http://edis.ifas.ufl.edu/cv118.

Tuelher, E. S., E. H. Silva, E. Hirose, R. N. C. Guedes, and E. E Oliveira. 2016. Competition between the phytophagous stink bugs Euschistus heros and Piezodorus guildinii in soybeans. Pest. Manag. Sci. 72: 1837-1843.

United States Department of Agriculture. 2005. Shipping point and market inspection instructions for tomatoes. USDA, Beltsville, MD. https://www.ams.usda.gov/sites/default/files/media/Tomato_Inspection_Instructions%5B1 %5D.pdf

United States Department of Agriculture, Economic Research Service. 2017. Organic market overview. USDA, Beltsville, MD. (https://www.ers.usda.gov/topics/natural-resources- environment/organic-agriculture/organic-market-overview/ )

68

Vallad, G., H. A. Smith, P. J. Dittmar, and J. H. Freeman. 2018. Vegetable production handbook of Florida. Farm Journal Media.

Webb, S. E., P. A. Stansly, D. J. Schuster, J. E. Funderburk, and H. Smith. 2013. Insect management for tomatoes, peppers, and eggplant. University of Florida. 1-40.

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BIOGRAPHICAL SKETCH

Alexander Gannon is from Hobe Sound, Florida and graduated from South Fork High

School in 2012. He attended the University of Florida, graduating in May of 2016 with a

Bachelor of Science degree in Biology. He enjoyed fishing with friends, exploring Gainesville’s natural trails, and swimming in the springs. Alexander participated in Dance Marathon, which raised money for UF Health Shands Children’s Hospital for three years in undergraduate studies.

In the fall of 2014, he started working as a research assistant at the University of Florida

Genetics Institute where he developed an interest in agricultural research. He attended a career expo for the College of Agricultural and Life Sciences where he discovered the Doctor of Plant

Medicine (DPM) graduate program.

Alexander began his DPM graduate studies in the fall of 2016 and developed an interest in entomology, so in 2017 he dual-enrolled in the DPM and Entomology and Nematology M.S. degree programs. During his graduate assistantship under Drs. Norman Leppla and Amanda

Hodges, he learned rearing techniques for Nezara viridula and strategies for integrated pest management (IPM). He assisted in developing an organic farming grant proposal along with designing and conducting trap cropping research for his thesis project. He also prepared and delivered professional presentations at meetings of the Entomological Society of America,

Southern Region Biological Control Working Group, and at organic vegetable production workshops. He has also participated in outreach for the Florida Farm Bureau, College of

Agriculture and Life Sciences, Doctor of Plant Medicine Student Organization, and the

Entomology and Nematology Student Organization. He plans to complete the DPM degree and graduate in the summer of 2020. His professional goal is to work in industry or government to advance integrated pest management.

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